Launch commit criteria are the criteria which must be met in order for the countdown and launch of a space shuttle or other launch vehicle to continue. These criteria relate to safety[citation needed] issues and the general success of the launch, as opposed to supplemental data.[1]

cumulus clouds with tops that extend into freezing temperatures within 5 to 10 miles (8.0 to 16.1 km)

19 kilometres (10 nmi) of the edge of a thunderstorm that is producing lightning for 30 minutes after the last lightning is observed.

field mill instrument readings within 9.3 kilometres (5 nmi) of the launch pad or the flight path exceed +/- 1,500 volts per meter for 15 minutes after they occur

thunderstorm anvil is within 19 kilometres (10 nmi) of the flight path

thunderstorm debris cloud is within 5.6 kilometres (3 nmi) or fly through a debris cloud for three hours

Do not launch through disturbed weather that has clouds that extend into freezing temperatures and contain moderate or greater[clarification needed] precipitation, or launch within 9.3 kilometres (5 nmi) of disturbed weather adjacent to the flight path

Do not launch through cumulus clouds formed as the result of or directly attached to a smoke[clarification needed] plume

Tanking will not begin if the 24-hour average temperature has been below 41 °F (5 °C), the wind is observed or forecast to exceed 42 knots (78 km/h; 48 mph) for the next three hour period, or there is forecast to be greater than a 20% chance of lightning within five nautical miles of the launch pad during the first hour of tanking.

After tanking begins, the countdown shall not be continued nor the Shuttle launched if any of the following weather criteria are exceeded:[citation needed]

Temperature

Once propellant loading has begun, the countdown will be stopped if the temperature remains above 99 °F (37 °C) for more than 30 consecutive minutes. The minimum temperature the countdown may proceed at is determined by a table of temperatures determined by wind speed and relative humidity ranging from 36 °F (2 °C) (high humidity, high winds) to 48 °F (9 °C) (low humidity, low winds). In no case may the space shuttle be launched if the temperature is 35 °F (2 °C) degrees or colder.

Wind

For launch the wind constraints at the launch pad will vary slightly for each mission. The peak wind speed allowable is 34 knots (63 km/h; 39 mph). However, when the wind direction is between 100 degrees and 260 degrees, the peak speed varies and may be as low as 20 knots (37 km/h; 23 mph).